| Natural Polysaccharides are abundant,renewable and green environmental natural resources,and widely applied in medicine,textile,food and many other fields.Natural polysaccharide aerogels,in the one hand,inherit advantages of natural polysaccharides and on the other hand,develop many other properties,which have great application potentials in drug loading,oil adsorption,heat insulator and other areas.In this work,cellulose aerogels and carboxymethyl cellulose(CMC)aerogels,with excellent properties,were obtained,using soluble and insoluble polysaccharides(cellulose and CMC)as raw materials and combing with sol-gel method,coagulation,controlled-release technology and freeze drying technique.And we also studied aerogels’ structural characteristics and forming mechanism.Compared with traditional preparation methods,this method possessed facile preparation process,mild reactive conditions,easy to control the formation of hydrogels and green environmental,et al.Furthermore,facing poor efficiency of oil pollution treatment and energy conservation and emission reduction,this work comprehensively analyzed and assessed polysaccharides’application prospect of oil adsorption,heat insulator and preparation of carbon materials.Meanwhile,to overcome deficiency of hydrophobic modification,cold plasma technology with trimethyl-chlorosilane(TMCS)as the plasm was employed for hydrophobic modification of aerogels.And we also studied its modification mechanism and adsorption rules.To study its heat-insulating properties,we proposed a novel compositing method of cellulose-silica hybrid aerogels and explored its compositing mechanism.To evaluate its application prospect in carbon aerogels,hydrothermal carbonization were conducted for cellulose and CMC aerogels,and we preliminarily analyzed its process,mechanism and properties of products.The results showed that cellulose aerogels with low density(low to 0.0196 g·cm-3),high porosity(up to 98.7%)and good mechanical properties were obtained,using cellulose as raw material,NaOH/urea as solvent,17wt%H2SO4 as coagulator.Compared with traditional hydrophobic modification methods,cold plasma technology with TMCS as the plasma was considerably more efficient(ca.150°),more rapid(less than 3 min),more stable and economically viable.Meanwhile,we also studied cellulose aerogels’ adsorption properties by statistical method,the results showed cellulose aerogels adsorption capacity(y)and density(x)follows the formula:y= 10.691+ 206.064/(1+(x/0.00448)^1.30226);cellulose aerogels adsorption capacity(y)and density of adsorbate follows the formula:y = 17.384 +0.229x;cellulose aerogels adsorption capacity(y)and viscosity of adsorbate follows the formula:y = 22.031 + 0.511e^(x/95.805).To evaluate polysaccharides’ application in heat-insulator area,cellulose-silica aerogels(CS)were prepared by a facile,energy saving and in-situ method,the CS aerogel has low density(0.052g·cm-3),high porosity(96.6%)and low thermal conductivities(0.0352 W/m·K),and the silica content is tunable,suggesting that CS aerogels have excellent heat-insulating properties.In order to obtain monolith CMC aerogels in a green way and explore effect of cross-linker’s concentration on CMC aerogels’ structural properties,in this work,bulk CMC aerogels with low density and high porosity were prepared using CMC as raw materials,FeCl3·6H2O-GDL as binary controlled-release cross-linker.The results showed CMC aerogels got optimal properties(density low to 0.0568g·cm3,porosity high to 90.45%),when the mass ratio of FeCl3·6H2O/CMC equals to 0.588.At the same time,by changing metal ions,various metal ions cross-linked CMC aerogels were prepared.Further treatment with hydrothermal carbonization(HTC),metal oxides-carbon hybrid nano materials,with different morphologies,such as nanorod,nanosphere and nanowire,et al.,could be obtained,and peculiar properties,such as magnetism and fluorescence property,could be introduced.Besides,we also carbonized raw cellulose under hydrothermal conditions and explored its HTC process and mechanism.The results showed that the onset of carbonization takes place at ca.220℃ and sulfuric acid has higher catalytic efficiency.It was supposed that at high pressure and temperature,sulfuric acid solution concentrated with evaporation of water,resulting in dehydration and carbonization of cellulose.On the other hand,S played a same role as B that the interaction of borax with sugar diols forms negatively charged complexes,catalyzing the isomerization to fructose,which can be dehydrated more easily as compared to glucose. |
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